私たちは翌日コンサートを開くことになっていた。

we; us

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

next day

concert

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to open; to undo; to unseal; to unpack; to bloom; to unfold; to spread out; to open (for business, e.g. in the morning); to be wide (gap, etc.); to widen; to hold (meeting, etc.); to give; to open; to found (nation, dynasty, sect, etc.); to open (a new business); to set up; to establish; to start; to open (ports, borders, etc.); to open (an account); to open up (new land, path, etc.); to clear; to develop; to open (a file, etc.); to extract (root); to reduce (equation); to cut open (fish); to change (kanji into hiragana); to flare (e.g. skirt); to slacken (into a poor posture)

thing; matter; incident; occurrence; event; something serious; trouble; crisis; circumstances; situation; state of affairs; work; business; affair; after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to; nominalizing suffix; pretending to ...; playing make-believe ...; alias; aka; nickname; alternative name; also known as

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

to become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...